Hydraulic shock absorber piston and cylinder construction



Oct. 15, 1946. M, MAGRUM 2,409,505

HYDRAULIC SHOCK ABSORBER PIS ION AND' CYLINDER CONSTRUCTION Filed Sept. 18, 1944 2 Sheets-Sheet 1 M Oct. 15, 1946,

s. M. MAGRUM 2,409,505 HYDRAULIC SHOCK ABSORBER PISTON AND CYLINDER CONSTRUCTION Filed Sept. 18, 1944 v 2 Sheets-Sheet 2 2 ZFEZ 22:1

Patented Oct. 15, 1946 'HYDRAULIC SHOCK ABSORBER PISTON AND CYLINDER CONSTRUCTION Gervase M. Magrum, Buffalo, N. Y., assignor to Houdaille-Hershey Corporation, Detroit, Mich, a corporation of Michigan Application September 18, 1944, Serial No. 554,578

18 Claims.

1 My invention relates to hydraulic structures, particularly to hydraulic dampers or shock absorbers of the so-called rotary type for use on automotiv or other vehicles, airplanes, and other structures for checking, damping and controlling-the relative motion between structural parts.

Heretofore hydraulic devices, such as rotary shock absorbers comprising a'cylinder structure and a piston structure oscillatable therein, have been constructed entirely of metal, such as steel, and such structures requireda large number of intricate, costly machining operations to obtain accurate fit. In'some prior art'st-ructures of this type non-metallic lining, as of plastic material, was provided in the cylinder structure to eliminate some of the machining operations necessary with metal, but in such structures the lining will loosen during operation of the shockabsorber with resulting leakage and corresponding impairment and decrease in the efficiency-of operation.

In accordance with nay-invention, the cylinder structure ina rotary hydraulic device-such asa shock absorber is entirely of plastic material, and

that part of the piston structure operable within the cylinder structure is exteriorly entirely of plastic material so that during-oscillation of the piston structure the contact between the piston structure and the cylinder structure will be entirely between the surfaces of plastic material,

there being just enough metal used inthe shock absorber assembly to hold the cylinder structure parts together and form reinforcement and protection therefor.

An important feature of my invention resides in a cup-shaped cylinder body withhydraulic abutment wings xtending therefrom and formed integral by melding of plastic material, and a pistongstructure whose inner end isin skeleton form around which is molded plastic'jmaterial maintaining accurate leakproof engagement'with the piston hub .and the cylinder walls respecabsorber secured as by welding to a metal reinforcing shell surrounding the cylinder body, to-- gether with various other metal elements for clamping the shaft bearing end wall to the cylinder body and for forming a hydraulic fluid reservoir for replenishing the hydraulic working chambers with hydraulic fluid.

The above referred to and other features of my invention are embodied in the structure shown on the drawings, in which:

Figure 1 is a front end view of the shock absorber with the end or closure wall removed;

Figure 2 is a section on plane II--I[ of Figure 1;

Figure 3 is a section on plane IIIIII of Figure 1;

Figure 4 is a diametral section of the hub end of the piston structure taken on line IV-IV of Figure3; and

Figure 5 is an inside elevation of a portion of the end closure wall showing the location of the replenishing flow passageways.

The cylinder body A is an integral structure accurately formed by molding of suitable plastic material. Itcomprises the base wall I0, and the annular cylindrical wall .I I from which the abutments i2 extend inwardly from diametrally opposite points, a cylindrical bearing boss IE on the base extending inwardly. The body A is received in a tubular metal shell or sheath I4 for reinforcing and protecting the cylinder body. The metal shell may be expanded by heating and the cylinder body then inserted therein so that when the shell .cools it will be tightly clamped around and against the cylinder body. A mounting base plate or metallic bar l5 extends through the diametrally extending channel it in the outer side of the base wall In and through the recesses H in the end of the shell l4, and this bar is preferably secured to the shell as by welding as indicated at It. This bar thus also functions as a key to hold, the cylinder body A in the shell HS against rotational displacement therein. The ends of the bar extending beyond the shell are provided with bolt holes 159 whereby the shock absorber cylinder structure will be mounted on a support.

'iThe endor closure Wall E for the cylinder body A- is also entirely of suitable plastic material accurately formed by molding. The end wall abuts the outer end of the cylinder wall II and the abutments i2 and i received within the annular cutwa-rdlyextending flange or lip 20 on the cylinder wall '5! to be heldaccurately concentric with the cylinder body A. The end-Wall is clamped in position by a. metal clamping ring of L- shaped cross-section whose peripheral leg 2| has threaded engagement in the outer end of the shell l4 for engagement of its radially inwardly extending leg 22 against the outer side of the end Wall E. In order that the wall B may be held against rotational movement relative to the body part A, the wall is provided on its inner side with circular recesses 23 for receiving the cylindrical bosses 24 formed on the outer ends of the abutments 12. The inner end of the clamping ring leg 2| abuts a metal washer 25 between which and the lip 29 on the body A suitable sealing material 25 is interposed which is compressed when the clamping ring is applied to form a sealing joint, the lip 29 preferably having the annular reces 2? around its outer side forming a spill or overflow space for the packing material.

The piston structure P has the metal shaft 28 which extends outwardly through the bearing opening 29 provided in the end Wall E. The inner end of the shaft is of enlarged diameter to form a cylindrical head 30 around which plastic material is to be molded to form the piston structure hub portion and piston vanes. As shown on Figures 3 and 4, the head 30 has wings 3| extending radially outwardly therefrom in diametrically opposite directions and these wings have holes 32 therethrough. The piston metallic structure is inserted into a mold for the molding therearound of suitable plastic material D which will intimately surround the wings 3| and extend through the holes 32 so as to lock the plastic material against axial and rotational displacement on the head 39. The cylindrical annular portion 33 of the plastic casing is of an outer diameter to engage with the cylindrical bearing surfaces 34 at the inner ends of the abutments l2. The portions 35 of the plastic cover surrounding the wings 3| will form the piston vanes which engage with their outer cylindrical surfaces against the inner cylindrical surface of the cylinder body A between the abutments l2, as shown on Figure 1. The outer portion 36 of the plastic material extends radially inwardly to the shaft 28 with its 45 draulic working chambers.

outer face in engagement with the inner face of the end wall B. The inner end portion 31 of the plastic material extends radially inwardly around the inner ends of the wings 3i and then axially inwardly around the inner edges of the 50 wings, the outer face of the portion 31 engaging with the bottom wall [3 of the cylinder body A. Thus, upon oscillation of the piston structure, the only surfaces having bearing engagement with each other will be the surfaces of the plastic ma- 55 heavy duty,

terial of the cylinder structure and the surfaces of the-plastic material on the piston structure, these surfaces being all accurately molded. The inner end portion 31 of the plastic material surrounding the piston structure receives the boss l3 which will provide a bearing support for the inner end of the piston structure.

Referring to Figure 1, the abutments I2 and the piston hub and vanes divide the space within the cylinder body A into hydraulic working cham bers 38, 38 and 39, 39. The outer portion of the piston structure shaft 28 has a bore 40 therethrough terminating in the bore 4| which communicates with the space 42 surrounded by the inner end portion 3'? of the plastic material on 70 the piston structure. This space is connected with the workin chambers 39, 39 through ports 43 formed in the plastic portion 31. The inner end of the shaft bore 49 is connected with the worktend through the head 30 of the piston structure and the surrounding plastic portion 33, as best shown on Figure 4. Any suitable valve means may be provided for controlling the flow between the working chambers 38, 38 and 39, 33. As shown on Figure 2, a valve seat plug 45 is inserted into the inner end of the bore 43 for engagement by a valve 46 whose stem 4'! extends outwardly through the bore to the exterior of the shaft and which stem has threaded connection with the bore 49 as shown at 48, so that when the valve stem is turned the valve will be set relative to the seat plug 52 for determining the resistance to the flow of hydraulic fluid which is displaced in the hydraulic working chambers during oscillation of the piston structure. The outer end of the shaft has a spline formation 49 thereon for receiving a suitable lever. When the shock absorber is applied on an automotive vehicle, the cylinder structure thereof is usually mounted on the vehicle chassis by means of the base plate [5, while the lever on the piston structure shaft is connected through suitable linkage usually with the axle of the vehicle. The valve stem may be provided on its outer end with a suitable arm or lever 59 whereby it may be readily turned for setting of the valve 46.

Referring to Figures 2 and 3, a cover 5|, preferably of sheet metal, is provided for the outer end of the shell l4. This cover has threaded engagement in the outer end of the shell, a sealing gasket 52 being provided. The inner portion 53 of the cover receives the shaft 28 and is deflected outwardly. Between the cover and the end wall B an annular abutment plate 54 receives the shaft and has its inner portion 55 deflected inwardly. Between these deflected portions 53 and 55 suitable packing and sealing material 55 surrounds the shaft and is held compressed against the shaft by the force of a spring 5'! between the plate and the end wall B.

The outer portion of the shell 14 and the end wall B and the cover 5| define a reservoir space 58 for hydraulic fluid for replenishing the hy- The replenishing passageways 59 are formed in the end wall B and are controlled by check valves 63 which are con fined within the passageways by pins 5 l. Through these passageways hydraulic fluid will flow from the reservoir 58 into the working chambers to keep these chambers filled with hydraulic fluid at all times A filler plug 62 is provided for the reservoir 58.

In shock absorbers that are subjected to sealing means are preferably provided for preventing leakage. For this purpose channels 63 are formed in the inner ends of the abutments I2 when the cylinder body A is molded. As shown, the channels may be rectangular to receive rectangular bars 64 of suitable sealing material through which cores 65 of metal or other suitable material extend, the sealing material being intimately bonded to the cores. The sealing bars are held intimately against the cylin- 65 drical surface of the plastic material portion of the piston structure to prevent leakage between working chambers past the abutments 12.

In the outer ends of the vanes 35, channels 6 3 are provided for receiving sealing bars 6'! for engagement with the inner surface of the wall H of the cylinder body A. As shown on Figure 3, the inner end portion 3'! of the plastic material on the piston structure may be provided with radial channels 38 for receiving sealing bars 69 ing chambers 38, 38 through ports 44 which exwhich engage against the bottom wall Hi of the .For' example, powdered light metal such as aluminum could be used, or suitable non-metallic plastic such as phenolic resin. The plastic could 1 also have fibrous or cotton filler. When the plastic is accurately molded under heavy pressure, the surfaces thereof will be dense and very smooth so that. with the oil in the shock absorber acting-as a lubricant, friction .between'the sealing bars and the surfaces. engaged thereby will be practically eliminated. With the light weight plasticma-terial, and the amount of metal in the shock absorber reduced to a minimum, the

. weightof the shock absorber will be greatly reducedwhile retaining maximum strength, and

the-shock absorber can be manufactured with much less cost and material and labor. With the bearing resistance reduced to a minimum, the life of the shock absorber will be greatly increased.

I haveshown andgdescribed a practical and efficient embodiment of the various features of my invention but I do not desire to belimited to the exactqconstruction, arrangement and operation shown. and described as changes and modifications may readily be made without departing fromithe scope of the invention as defined in the appended claims.

I I claim as my invention:

1. In a hydraulic device of the type described,

.acylinder-structure formed entirely of molded plastic material; a piston structure whose outer portion is of molded plastic material for bearing engagement with surfaces insaid cylinder structure, andymetallic protective and support-- ing means for said cylinder structure.

Ina hydraulic. device for the purpose described, a cylinder structure formed entirely of molded plastic material, a piston structure oper- .able in said cylinder structure, pistonstructure beingrotatable within said cylinder structure to .act upon liquid .whiclnmay be contained within the cylinder, and a supporting structure for' holding said cylinder structure stationary.

3. In a hydraulic damping device, a cylinder structure comprising a cylindrical cup-shaped body molded integral of plastic material, an end wall for said body molded integralof plastic material and having a bearing passageway therethrough, a piston structure comprising a head within said cylinder structure and a. shaft extending outwardly through said bearing passageway, said head being surrounded by plastic material intimately molded thereto to present surfaces for cooperation with surfaces in said cylinder structure.

4. In a hydraulic dampin device, a cylinder structure comprising a cylindrical cup-shaped body molded integral of plastic material, an end wall for said body molded integral of plastic mater al and having a bearing passageway therethrough a piston structure comprising a head within said cylinder structure'and a shaft extending outwardly through said bearing passageway, said head being surrounded by plastic material intimately molded thereto to present surfaces for cooperation with surfaces in said cylinder structure, and a reinforcing tubular metal shell intimately surrounding said cylinder structure.

5. In a hydraulic damping device, a cylinder structure comprising a cup-shaped body part in the form of an integral molding of plastic material with; abutments extending radially therefrom, an end wall for saidbody in the form of an integral molding of plastic material and having a bearing passageway therethrough, a piston structure comprising a head Within the cylinder structure and a shaft extending through and having bearing supportin said bearing passageway, said head being surrounded by plastic material intimately molded thereto and defining a cylindrical hub portion for bearing engagement withsa'id abutments and radially extending vanes for bearing engagement with the cylinder surface of said cylinder structure between said abutments.

6. In a hydraulic damping device of the type disclosed, a cylinder structure, a piston structure having a head within the cylinder structure and a shaft extending outwardly therefrom, said head having wings extending therefrom, and plastic material intimately molded around said head and wings to provide surfaces for engagement with surfaces of said cylinder structure.

7. In a hydraulic damping device, a cylinder structure enclosing a cylinder space and having abutments extendin into said space, a piston structurecomprising a metallic shaft terminating in a head in said cylinder space having radial projections thereon, plastic material intimately molded around said head and said projections to form a hub portion for engagement with said abutments and vanes for engagement with said cylinder structure between said abutments.

8. In a rotary hydraulic shock absorber, a cylinder structure of plastic material, a tubular metal shell intimately receiving said cylinder material, a reinforcing tubular metal shell intimately receiving said cylinder structure, said cylinder structure having a diametral channel in its end and the end of said shell having recesses in alignment with said channel, and a metal supporting bar extending through said channel and recesses and being welded to said shell whereby to hold said cylinder structure against rotatable displacement in said shell.

10. In a rotary shock absorber of the type described, a vaned piston structure comprising a metal shaft terminating in a head having projections thereon, and plastic material intimately molded around the head and projections to form a cylindrical hu-b portion with vanes extending therefrom.

11. In a rotary hydraulic shock absorber construction, a cylinder structure of plastic material, a tubular metal shell intimately receiving said cylinder structure, said cylinder structure having a diametrically extending channel in its end, and a keying member within said channel and cooperating with said metal shell and said cylinder structure whereby to hold said cylinder structure against rotary displacement in said shell.

12. In combination in a cylinder structure for a rotary hydraulic shock absorber, said cylinder structure being formed of plastic material, a reinforcing and supporting structure including means for securing the cylinder in place on a structure with which the shock absorber is to be used, said cylinder structure and said reinforcing and supporting structure being keyed together against relative rotary displacement.

13. In combination in a hydraulic shock absorber construction, a cylinder formed of plastic material and being of generally cup shape, a rotatable piston co-operable within said cylinder and having a stem projecting substantially beyondthe open end of the cylinder, 9. plastic closure cap over the open end of the cylinder and having a bearing opening therethrough co-operating with said piston stem, and means engaging and clamping said cap onto said end of the cylinder.

14. In combination in a hydraulic shock absorber construction, a cylinder structure comprising a cylindrical cup-shaped body molded of plastic material, a piston structure comprising a head within said cylinder structure and a shaft extending outwardly beyond the open end of the cylinder cup, a closure cap for the cylinder formed of plastic material and having a bearing passageway therethrough for said shaft, a reinforcing tubular metal shell intimately surrounding said cylinder structure and projecting beyond the capclosed end thereof, and a, clamping ring threaded into the projecting portion of the metal shell and engaging said cap to secure the latter in place on the end of the cylinder structure.

15. In combination in a hydraulic shock absorber construction, a cylinder structure comprising a cylindrical cup-shaped body molded of plastic material, a, piston structure comprising a head within said cylinder structure and a shaft extending outwardly beyond the open end of the cylinder cup, a closure cap for the cylinder formed of plastic material and having a bearing passageway therethrough for said shaft, a reinforcing tubular metal shell intimately surrounding said cylinder structure and projecting beyond the capclosed end thereof, a clamping ring threaded into the projecting portion of the metal shell and engaging said cap to secure the latter in place on the end of the cylinder structure, said cap being of smaller diameter than the interior diameter of said shell, and liquid sealing means within the space provided between the periphery of the cap and the opposing wall of the metal shell, said clamping ring being constructed and arranged 8 to drive said sealing means toward the end portion or the cylinder exposed within said space and into sealing engagement with the contiguous wall surfaces of the cap and metal shell at said exposed end portion.

16. In combination in a hydraulic shock absorber construction, a cylinder structure comprising a cup-shaped molded plastic body, a rotary piston structure within said cylinder structure and having a shaft projecting therefrom, a closure member of molded plastic material for the open end of the cylinder structure and having a bearing passage therethrough for the piston shaft, interengaging means on said cylinder structure and said closure member holding them against relative rotation, and means for securing the cylinder structure and closure member together.

17. In combination in a hydraulic shock absorber construction, a cylinder structure comprising a cylindrical cup-shaped body molded of plastic material, a reinforcing tubular metal shell intimately surrounding said cylinder structure and projecting substantially beyond the open end of the cylinder structure, a plastic closure cap for said open end Of the cylinder structure cooperating with the metal shell for securing the cap in place, a closure cap for the projecting end of the metal shell and spaced from said cylinder closure cap to provide a substantial liquid chamber between the two caps, said plastic cap having means affording communication between said chamber and the interior of the cylinder, and a rotary piston Within said cylinder held in place by said plastic cap and having a shaft projecting out through both of the caps.

18. In combination in a, hydraulic shock absorber construction, a cylinder structure having an end wall, a rotary piston within the cylinder and comprising a metallic head spaced at its inner end from said end wall and surrounded by plastic material intimately molded thereto and defining a cylindrical hub portion for bearing engagement with the cylinder wall, said hub portion having the inner end thereof projecting beyond the inner end of the metallic head to engage said end wall and defining a fluid chamber between the inner end of said head and the end wall.

GERVASE M. MAGRUM. 

